United States
Environmental Protection
Agency
Atmospheric Sciences
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S3-86/047 Feb. 1987
v>EPA Project Summary
Toxic Chemicals in the
Environment: A Program of
Field Measurements
H. B. Singh, R. J. Ferek, L J. Salas, and K. C. Nitz
An environmental mobile laboratory was
instrumented and employed to perform a
series of eight field studies of one-to-three
weeks duration during which around-the-
clock measurements of organic chemicals
were performed in six United States sites
under a variety of meteorological condi-
tions. Field studies involved on-sfte analy-
sis of 29 organic chemicals, many of
which are mutagens or suspect carcino-
gens. Chemicals measured included chlor-
ofluorocarbbns, halomethanes, haloeth-
anes, halopropanes, chlorinated alkenes,
aromatic hydrocarbons, organic nitrogen
compounds and aldehydes. The measured
data are reported as mixing ratios and in-
terpreted In the context of their mean diur-
nal behavior and chemical removal rates.
Except for aromatic hydrocarbons and
aldehydes, average concentrations of
measured species were hi the O-to-5 ppb
range. The average concentration range
for aromatics and aldehydes was in the
0-25 ppb range. Maximum measured con-
centrations were typically 5 to 10 times
the mean values. Typical diurnal profiles
showed highest concentrations in the
night and early morning hours. Minimum
values observed in the afternoon were
probably due to deep vertical mixing.
Studies in San Jose, CA, clearly snowed
the effect of meteorology with mean con-
centrations rising four to seven times nor-
mal values under stagnant conditions. Am-
bient data suggest that aldehydes are less
abundant In whiter. Interpretation of aro-
matic hydrocarbon data from southern
California showed that the prevailing
hydroxyl radical concentrations of 2.6 x
106 molec. cm~3 in February are not
significantly different from values deter-
mined for summer. Analysis of historic
data further suggests that the concentra-
tions of benzene (the dominant toxic
chemical in ambient air) have declined by
a factor of about 10 in the ambient air of
southern California over the last two
decades.
This Project Summary was developed
by EPA's Atmospheric Sciences Research
Laboratory, Research Triangle Park, NC, to
announce hey findings of the research pro-
ject thatisfuHy documented h a separate
report of the same Me (see Project Report
ordering information at back).
Introduction
Over the last three decades large
amounts of a growing number of synthetic
organic chemicals have been released into
the ambient environment. Urban atmos-
pheres contain a complex mixture of
chemicals, many of which are known to
be toxic at concentrations significantly
higher than those encountered in typical
ambient atmospheres. The degree to
which the general ambient environment
contributes to human cancer is a matter
of both active research and debate. A
report from the Office of the U.S. Surgeon
General concluded that "toxic chemicals
are adding to the disease burden of the
United States in a significant, although as
yet not precisely defined way" (U.S.S.G.,
1980). The process of understanding the
risks associated with exposure to poten-
tially hazardous chemicals requires a
determination of the ranges of concentra-
tions that can be found in the ambient air.
This study was initiated primarily to
measure the atmospheric concentrations
of a variety of potentially hazardous
-------
gaseous organic chemicals* at selected
urban locations under varying meteoro-
logical and source-strength conditions.
The chemicals were sampled and analyzed
on site using a suitably outfitted mobile
laboratory. The overall program of analyt-
ical methods development, field measure-
ments, data collection, and data analysis
is expected to provide information that will
permit a better assessment of the atmos-
pheric abundance and chemistry of this
potentially harmful group of chemicals.
Procedures
Because of problems associated with
surface reactions, the integrity of an air
sample is best maintained when only
nominal amounts of air samples are col-
lected, and the time between collection
and analysis is kept to a minimum. In this
study, an on-site field analysis program
was devised to meet these requirements.
The sampling manifold was all stainless
steel with a variable inlet height.(Always,
the sampling manifold was adjusted to be
higher than nearby structures; a typical
manifold inlet height was 5 m above
ground.) For pumping and pressuring air
samples, a special stainless-steel metal
bellows compression pump (Model MB
158) was always used. For the analysis of
aldehydes, surface air was sampled in an
all-glass apparatus.
For all of the measured halogenated
species and organic nitrogen compounds,
electron-capture detector (ECD) gas chro-
matography (GO was the primary means
of analysis. The aromatic hydrocarbons
were measured using flame-ionization
detector (FID) gas chromatography. For-
maldehyde and acetaldehyde were meas-
ured by analyzing the 2,4-dinitrophenyl-
hydrazine derivatives formed by reaction
of 2,4-dinitrophenylhydrazine (DNPH) with
aldehydes, using high-performance liquid
chromatographic (HPLC) methods.
All GC channels were equipped with
stainless-steel sampling valves and could
be operated either with a direct sampling
loop or with a preconcentration trap. In no
instance was a sample size of greater than
one liter used. Usually, sample volumes of
500 ml or less were satisfactory.
Two types of sampling procedures were
employed. During the first five field pro-
grams, an on line 2-liter SUMMAR polish-
ed stainless steel canister was pressurized
to 32 psi during a three to five minute per-
iod, and this air was used for GC analysis.
'The term "hazardous chemicals" as used here is not
intended to imply that a proven human health hazard
exists. Usually, toxicity studies are incomplete or
inconclusive and involve extrapolation of animal data
to humans.
During the last three field programs at
San Jose, CA, a different sampling ar-
rangement was used to provide two-
hourly integrated samples. An evacuated
6-liter SUMMAR polished stainless steel
canister was slowly pressurized using a
metal bellows pump and a mass flow con-
troller. In this manner, about 18 liters (STP)
of air were pumped into the 6-liter canister
over a two-hour period.
Eight field studies were performed in the
following six select urban environments in
the continental United States:
Philadelphia, Pennsylvania
Staten Island, New York
Downey, California
Houston, Texas
Denver, Colorado
San Jose, California
Within the above cities, specific sites were
chosen that represented an open urban
area. Large point sources or topographical
features that could affect the represent-
ativeness of the measurements were
avoided. Every attempt was made to
select sites that could be expected to be
indicative of general pollution levels prev-
alent in the area. It must be emphasized
that only one site within each of the
selected cities was monitored. The data
collected here, while perhaps typical of
general ambient environment, are truly
representative only of the specific site
monitored.
The site locations and the periods of
field measurements are shown in Table 1.
On the average each field study was of
roughly two weeks duration with a range
of one to three weeks. Based on our past
experience we believed that significant
night and daytime differences were likely
in the abundance of organic chemicals.
Thus we concluded that despite the logis-
tical difficulty, a 24-hour measurement
schedule offered the most efficient means
to collect the maximum amount of data
needed to characterize the burden of tox-
ic organic chemicals in the ambient air.
Additionally, night abundances of trace
chemicals were likely to provide important
information about the sources and sinks
of measured species. Therefore, a 24-
hour-per-day, seven-days-a-week measure-
ment schedule was followed during all
field programs.
Results
The data collected during these studies
have been compiled, validated, and statis-
tically summarized. The statistical sum-
maries of all field data are presented in
Tables 2, 3, and 4. All concentrations are
expressed in units of parts per trillion by
volume (pptv -10~12 v/v). Quantities tab-
ulated are the means and standard devia-
tions (one sigma), maximum and minimum
concentrations, and the number of posi-
tive (nonzero) measurements as well as
the total number of measurements per-
formed. These statistics include all meas-
ured data. When the concentration was
below our detectable limit, it was assigned
a value of zero. Usually, values were not
below detection.
Conclusions and
Recommendations
The measurements were analyzed to
see if seasonal cycles or long-term trends
were discernible in the data. The role of
seasonal cycles was examined by consid-
ering the concentrations of selected an-
thropogenic species as measured at the
San Jose site during April, August, and
December. During the December experi-
ment, a high-pressure system blanketed
the area pushing carbon monoxide levels
to 14 ppm (the highest in five years). A
mixing depth of less than 20 meters was
frequently encountered. Although emis-
sions of these chemicals probably vary
seasonally, there is every indication that
this is a small change compared to the ef-
fect of the meteorological parameters
observed during the December experi-
ment. This four-to-six fold increase implies
local sources and shallow mixed layer. For
chemicals like carbon tetrachloride, where
little or no local sources may exist, the at-
mospheric levels are nearly invariant. Fur-
ther analysis is needed to establish the
relationship between ambient levels and
meteorological conditions. It is not pos-
sible from this data to conclude that
winter levels in San Jose are typically
higher than summer levels. To the extent
that the boundary layer is deeper during
summer, it is reasonable to assume that
reduced summer levels may prevail. Super-
imposed on the meteorological conditions
are variations in emissions (which are also
not known for any given city) and chem-
ical removal processes.
Data from four cities which were re-
visited after several years were also
analyzed. One can perhaps conclude that
the levels of methylene chloride and
trichloroethylene have declined over the
last four to five years. However, no defin-
itive seasonal or long-term trends can be
established without a clear knowledge of
the emissions and meteorological condi-
tions. While detailed meteorological analy-
sis is beyond the scope of this study, it
may be possible to analyze these data in
the future in the context of prevailing
meteorology. Any attempt to estimate
-------
human exposure from these measure-
ments must also employ meteorological
analysis for temporal extrapolation.
Because of the source complexity and
wide variations in meteorological param-
eters, short-term experiments such as
those performed here are inadequate for
establishing long-term trends.
Although these studies were of short-
term duration, our practice of around-the-
clock operation allowed for extensive data
collection. The degree of temporal and
spatial variability in the atmospheric abun-
dance of toxic chemicals is clear from data
presented. Typical concentrations of most
chemicals measured were in the sub-ppb
range with the exception of aromatic
hydrocarbons and formaldehyde (where
average concentrations in the 1-to-25 ppb
range were encountered). For most pre-
dominantly man-made chemicals, average
concentrations in urban atmospheres were
one-to-two orders of magnitude higher
than in clean remote atmospheres.
Meteorology appeared to play a strong
role in the average abundance as well as
in the diurnal behavior of these chemicals.
Typical diurnal profiles showed highest
concentrations in the night and early
morning hours and minimum values in the
afternoon, probably due to deep vertical
mixing at this time. The diurnal patterns
in San Jose were somewhat different but
they also clearly showed the effect of
meteorology on the abundance of chem-
icals. Mean concentrations under severe
stagnant conditions encountered at San
Jose rose to 4-to-7 times normal values.
Ambient data suggest that aldehydes are
less abundant in winter compared to sum-
mer months. Interpretation of aromatic
hydrocarbon data in southern California
showed that the prevailing hydroxyl radical
concentrations of 2.6 x 106 molec. cm~3
in February are not significantly different
from values computed for summer. This
is in apparent contradiction to a commonly
made assumption that winter hydroxyl
levels are much lower.
On the whole, we conclude that typical
urban atmospheres contain chemicals that
are known to be toxic at much higher con-
centrations. Exposures to ambient levels
of these species are highly variable. The
task of characterizing the atmosphere
with which this study is most concerned
is itself, at best, highly incomplete. Much
more atmospheric and toxicity data will be
needed to determine the risks associated
with long-term exposures to low levels of
toxic species.
Table 1. Field Sites and Measurement Schedule
Experiment Experiment
No. City Period
1 Philadelphia, PA
2 Staten Island, NY
3 Downey, CA
4 Houston, TX
5 Denver, CO
6 San Jose, CA
7 San Jose, CA
8 San Jose, CA
4-22 April 1983
25 April - 1 May 1984
18-27 February 1984
9-17 March 1984
24 March - 1 April 1984
4-16 April 1985
12-24 August 198S
13-21 December 1985
Site Address
Lycoming and Castor St.
Wild Ave. and Victory Blvd.
7601 East Imperial Rancho
Los Amigos Hospital
Mae St. and 1-10 Frontage
Road
Marion and £ 51 St.
Alma and Senter Road (San
Jose Historic Museum)
Alma and Senter Road (San
Jose Historic Museum!
Alma and Senter Road (San
Jose Historic Museum)
Table 2. Atmospheric Concentrations of Measured Chemicals for Philadelphia and Staten Island
Philadelphia
4-22 April 1983
Staten Island
25 April - 1 May 1983
Chemical Group and Species
CMorof/uorocarbons:
Trichlorofluoromethane (F-11)
Dichlorodifluoromethane (F-12)
Trichlorotrifluoroethane (F-1131
Dichlorotetrafluoroethane (F-114)
Halomethanes:
Methyl chloride
Methyl bromide
Methyl iodide
Methylene chloride
(Dichloromethanet
Chloroform (Trichloromethane)
Carbon tetrachloride
Haloethanes and Halopropanes:
Ethyl chloride
1, 2-Dichloroethane
1,2-Dibromoethane
1, 1, 1-Trichlomethane
Mean3
369
595
41
769
47
3
622
60
28O
66
21
491
S.D."
182
279
88
299
30
3
559
39
220
125
49
25
PPTV
Maximum
1667
2474
616
2883
124
9
3098
272
2O15
555
r-
436
2679
Minimum
211
340
10
348
23
0.8
121
12
126
<10
<5
164
n/N°
88/88
88/88
76/76
91/91
34/34
8/8
91/91
146/146
171/171
19/19
144/147
1 72/1 72
Mean
284
566
24
654
80
5
1109
88
387
47
19
403
S.D.
110
269
13
280
96
2
1614
53
310
28
8
257
PPTV
Maximum
614
1554
80
1367
447
9
8868
279
1475
107
41
1435
Minimum n/N
137
296
10
328
25
3
243
27
131
21
8
120
33/33
32/32
'
31/31
33/33
23/23
21/21
34/34
54/54
66/66
11/11
58/58
66/66
(Continued)
-------
Table 2.
Atmospheric Concentrations of Measured Chemicals for Philadelphia and Staten Island
Philadelphia
4-22 April 1983
Staten Island
25 April - 1 May 1983
PPTV
PPTV
Chemical Group and Species Mean* S.D.* Maximum Minimum n/N° Mean S.D. Maximum Minimum
n/N
1,2-Dichloropropane 72 91 560 18 140/140 41 17 80 <10 54/54
Chloroalkenes:
Trichloroethylene 149 173 1003 12 166/166 164 188 1021 12 63/63
Tetrachloroethylene 570 529 4337 76 284/284 792 901 4793 127 117/117
Aromatic Hydrocarbons:
Benzene 1917 1721 11074 269 293/293 4367 6620 33960 117 99/99
Toluene 4260 4141 30576 382 287/297 7436 9340 44672 462 100/100
Ethyl Benzene 760 778 7256 85 264/297 2678 4186 16648 <50 76/100
m/p-Xylene 1598 1489 14050 194 283/297 2635 3286 15594 <50 83/100
o-Xylene 847 847 5852 <50 232/297 2596 3549 17353 <5O 56/1OO
3/4-Ethyl toluene 714 636 3891 <50 192/297 1603 1597 6644 <50 46/100
1,3,5-Trimethyl benzene 526 333 1374 <50 31/297 1565 1814 7286 <50 24/100
1,2,4-Trimethyl benzene 943 757 5363 <50 222/297 2858 4841 29696 <50 54/100
Oxygenated Species:
Pemxyacetylnitrate (PAN) 1068 678 3721 <50 281/309 1578 1111 5475 386 116/116
Peroxypropionylnitrate (PPN) 139 94 501 <50 280/309 213 150 902 <50 116/118
Formaldehyde __________
Acetaldehyde __________
'Arithmetic Mean.
bOne standard deviation.
cn is the number of positive (non-zero) measurements;
N is the total number of valid measurements.
Table 3. Atmospheric Concentrations of Measured Chemicals for Downey, Houston, and Denver
Downey
18-27 February
Chemical Group and Species
Ch/orofluorocarbons:
Trichlorofluoromethane IF-111
Dichlorodifluoromethane (F-12)
Trichlorotrifluoroethane IF-113)
Dichlorotetrafluoroethane (F-114)
Halomethanes:
Methyl chloride
Methyl bromide
Methyl iodide
Methylene chloride
(Dichloromethane)
Chloroform (Trichloromethane)
Carbon tetrachloride
Haloethanes and Halopropanes:
Ethyl chloride
1,2-Dichloroethane
1,2-Dibromoethane
1,1,1-Trichloroethane
1,2-Dichloropropane
Chloroalkenes:
Trichloroethylene
Tetrachloroethylene
Aromatic Hydrocarbons: '
Benzene
Toluene
Ethyl Benzene
m/p-Xytene
o-Xylene
Mean8
685
1183
118
34
792
212
3
2399
135
199
28
102
102
1161
35
184
1471
8720
16890
4580
10210
4180
S.D.b
356
779
53
20
237
226
2
1604
81
71
17
134
83
609
34
155
694
5940
12251
3712
7785
3219
PPTV
Maximum
1718
3641
313
89
1655
815
10
6641
385
331
106
630
420
2727
157
738
3711
28790
63970
16O90
37480
15960
1984
Minimum
168
314
48
12
470
18
<1
443
26
103
11
20
<5
161
<2
22
341
970
1640
280
920
<50
Houston
9-17 March 1984
n/rf
45/47
48/48
47/47
47/47
48/48
44/44
45/45
47/47
64/64
48/48
43/43
45/45
52/61
64/64
43/64
64/64
64/64
107/107
106/1O6
104/104
104/104
103/103
Mean
488
512
58
18
961
23
12
324
249
291
448
450
293
375
158
61
169
6130
7270
1540
3340
1380
S.D.
142
156
16
3
361
8
10
300
243
175
871
673
550
208
108
106
245
5838
9479
1589
3066
1389
PPTV
Maximum
1041
941
114
30
2278
48
51
1584
1588
1154
2981
2456
3181
1235
724
880
1604
40320
78160
8200
17910
7200
Minimum
251
332
36
12
520
11
2
71
47
158
11
<5
<5
121
<2
<2
20
1030
270
<50
<50
<50
n/N
48/48
48/48
48/48
47/47
47/47
45/45
47/47
46/46
110/110
48/48
40/44
47/48
104/106
1 10/1 10
100/106
104/1 10
109/109
102/102
100/102
99/102
101/102
89/102
(Continued)
-------
Table 3. (Continued)
Downey
18-27 February 1984
Houston
9-17 March 1984
PPTV
PPTV
Chemical Group and Species Mean8 S.D.b Maximum Minimum n/ff Mean S.D. Maximum Minimum
n/N
3/4-Ethyl toluene
1,3,5-Trimethyl benzene
1,2,4-Trimethyl benzene
3220
850
4020
2512
923
3324
12270
4O4O
15590
<50
<5O
<50
102/103
63/104
100/104
770
no
990
890
714
1005
5920
6760
7180
<50
<50
<50
84/102
20/102
76/102
Oxygenated Species:
Peroxyacetylnitrate (PAN) 1231 1112 6671 67 207/207 751 787 7925 <50 188/193
Peroxypropionylnitrate (PPN) 60 67 403 <50 145/206 45 78 538 <50 89/189
Formaldehyde 15500 5900 41000 2000 48/48 3800 8300 22500 <4OO 11/11
Acetaldehyde 8500 6300 28400 10OO 48/48 2200 1700 6700 <2OO 11/11
Tabl»3.
(Continued)
Denver
24 March - 1 April 1984
Chemical Group and Species
Chlorofluorocarbons:
Trichlorof/uoromethane IF-11)
Dichlorodifluoromethane (F-12)
Trichlorotrifluoroethane IF-113)
Dichlorotetrafluoroethane (F-114)
Halomethanes:
Methyl chloride
Methyl bromide
Methyl iodide
Methylene chloride
(Dichloromethane)
Chloroform (Trichloromethane)
Carbon tetrachloride
Haloethanes and Halopropanes:
Ethyl chloride
1,2-Dichloroethane
1,2-Dibromoethane
1, 1, 1-Jrichloroethane
1, 2-Dichlompropane
Chloroalkenes:
Trichloroethylene
Tetrachloroethylene
Aromatic Hydrocarbons:
Benzene
Toluene
Ethyl Benzene
m/p-Xylene
o-Xylene
3/4-Ethyl toluene
1,3,5-Trimethyl benzene
1,2,4-Trimethyl benzene
Oxygenated Species:
Peroxyacetylnitrate (PAN)
Peroxypropionylnitrate (PPN)
Formaldehyde
Acetaldehyde
Mean3
555
648
41
26
780
22
2
569
123
264
23
23
122
647
163
53
434
2230
3340
11OO
1900
630
440
80
650
644
22
2300
1000
S.D.b
89
546
41
8
227
11
1
456
40
26
21
29
84
320
62
49
419
2081
3871
3454
2322
1142
707
221
972
348
29
180O
500
PPTV
Maximum
770
2811
282
64
1602
64
8
2699
259
363
123
124
601
1850
312
241
2499
13480
25780
31480
14770
6630
4220
1300
5650
2039
85
5500
2100
Minimum
412
334
22
17
573
13
1
104
38
225
9
<5
<5
256
<2
5
51
380
390
<50
<50
<50
<50
<50
<50
191
<50
<400
<200
n/N°
42/42
42/42
42/42
41/41
41/41
41/41
42/42
42/42
98/98
42/42
41/41
31/38
98/99
98/98
96/97
99/99
99/99
85/85
85/85
70/85
82/85
50/85
48/85
14/85
53/85
209/209
82/209
21/21
21/21
"Arithmetic Mean.
bOne standard deviation.
cn is the number of positive (non-zero! measurements;
N is the total number of valid measurements.
-------
Table 4.
Atmospheric Concentrations of Measured Chemicals for San Jose
4-16 April 1985
12-24 August 1985
PPTV
PPTV
Chemical Group and Species Mean* S.D.b Maximum Minimum n/ff
Mean
S.D.
Maximum Minimum
n/N
Chlorofluorocarbons:
Trichlorofluoromethane IF-11)
Dichlorodifluoromethane IF-12)
Trichlorotrifluoroethane (F-1131
Dichlomtetrafluoroethane (F-114)
529
1020
1256
59
217
477
755
39
1613
2751
4605
239
252
458
395
19
1 19/1 19
117/117
117/117
115/115
450
881
616
72
179
345
407
143
1330
2058
2410
888
244
427
166
12
127/127
129/129
126/126
123/123
Halomethanes:
Methyl chloride
Methyl bromide
Methyl iodide
Methylene chloride
(Dichloromethane)
Chloroform (Trichloromethane)
Carbon tetrachloride
Haloethanes and Halopropanes:
Ethyl chloride
1,2-Dichloroethane
1,2-Dibromoethane
1,1,1-Trichloroethane
1,2-Dichloropropane
Chloroalkenes:
Trichloroethylene
Tetrachloroethylene
Aromatic Hydrocarbons:
Benzene
Toluene
Ethyl Benzene
m/p-Xylene
o-Xylene
3/4-Ethyl toluene
1,3,5-Trimethyl benzene
1,2,4-Trimethyl benzene
Oxygenated Species:
Peroxyacetylnitrate (PAN!
Peroxypropionylnitrate (PPNI
Formaldehyde
Acetaldehyde
1060
400
5
1534
64
193
21
360
31
63
427
3296
5667
1213
3619
1361
1023
224
1272
274
549
6
906
27
51
7
174
14
48
259
2239
4206
1108
2701
950
756
208
832
2508
4661
51
4311
138
398
41
905
70
266
1530
11747
22155
6355
14641
5085
4066
1608
4518
673
44
1
403
23
55
9
120
9
8
58
379
637
131
649
121
128
69
233
116/116
114/114
104/104
117/117
119/119
119/119
40/40
118/118
87/87
113/113
115/115
123/123
122/122
122/122
122/122
119/119
120/120
121/121
116/116
121
3
1119
58
144
283
25
68
264
2060
3904
859
1981
913
649
168
715
146
2
1056
35
20
68
9
54
169
1258
2742
736
1431
659
433
124
521
1067
8257
180
213
518
61
266
767
7816
19612
4088
8380
5125
2927
773
3591
<5
1
142
11
85
133
9
10
36
441
709
173
515
216
147
34
112
112/114
128/128
128/128
139/139
142/142
142/142
136/136
141/141
139/139
145/145
145/145
144/144
140/140
141/141
142/142
141/141
135/135
Table 4.
(Continued)
13-21 December 1985
PPTV
Chemical Group and Species
Mean8 S.D.b Maximum Minimum n/N°
Chlorofluorocarbons:
Trichlorofluoromethane IF-11) 585 170 971 239
Dichlorodifluoromethane (F-12) 1435 376 2450 670
Trichlorotrifluoroethane IF-113) 1211 351 2321 476
Dichlomtetrafluoroethane (F-114) 227 245 967 34
Halomethanes:
Methyl chloride 1118 581 4870 194
Methyl bromide 2869 3098 15424 239
Methyl iodide 9 4 23 3
Methylene chloride
(Dichloromethane) 4181 1795 10310 1034
Chloroform (Trichloromethane) 102 38 203 38
Carbon tetrachloride 155 43 266 90
Haloethanes and Halopropanes:
Ethyl chloride
1,2-Dichloroethane - - - -
1,2-Dibromoethane 7 3 18 2
1,1,1-Trichloroethane 1219 721 3174 345
1,2-Dichloropropane 24 5 35 9
80/80
91/91
92/92
94/94
92/92
92/92
80/80
91/91
93/93
93/93
61/61
93/93
85/85
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Table 4. (Continued)
13-21 December 1985
PPTV
Chemical Group and Species Mean8 S.O.* Maximum Minimum n/ff
Chloroalkenes:
Trich/oroethylene 271 194 907 71 93/93
Tetrachloroethylene 1858 1202 6639 311 93/93
Aromatic Hydrocarbons:
Benzene 12372 4501 23425 3921 95/95
Toluene 21155 8801 45947 6676 95/95
Ethyl Benzene 6176 3046 14453 1553 95/95
m/p-Xylene 13144 5809 25330 3672 95/95
o-Xylene 5714 2170 11001 2024 95/95
3/4-Ethyl toluene 4224 1574 8285 1476 95/95
1,3,5-Trimethyl benzene 1298 575 2662 254 95/95
1,2,4-Trimethyl benzene 5367 1903 10376 1838 95/95
Oxygenated Species:
Peroxvacetylnitrate (PAN) _____
Peroxypropionylnitrate (PPN) _____
Formaldehyde _____
Acetaldehyde _____
"Arithmetic Mean.
bOne standard deviation.
cn is the number of positive (non-zero) measurements;
N is the total number of valid measurements.
-------
H. B. Singh, R. J. Ferek, L J. Sales, and K. C. Nitz are with SRI International,
Menlo Park, CA 94025.
L. T. Cupitt is the EPA Project Officer (see below).
The complete report, entitled "Toxic Chemicals in the Environment: A Program
of Field Measurements," (Order No. PB 86-239 910/AS: Cost $16.95, subject
to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Atmospheric Sciences Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use 5300
EPA/600/S3-86/047
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